Kyrgios had the first break point of the match at 2-2 in the first set, but sent a forehand wide to blow the chance.

Dimitrov, however, took full advantage of his one break opportunity when Kyrgios netted a forehand to take a 4-2 lead.

Kyrgios showed his frustration by remonstrating with the chair umpire during the second set over line umpiring.

He hit 15 aces to six but was weaker on serve throughout, winning only 36 per cent of points on his second-serve in the second-set.

After a rain delay caused him to complete two matches in a day, he did not have the fitness to go with Dimitrov.

“I was struggling a couple of weeks ago and he got me out on the practice court. We practised for an hour-and-a-half and I was struggling and he was fresh,” Kyrgios said.

“You had me mentally today already. I was like, ‘I know this guy’s fitter than me’.”

Kyrgios has not won a tournament this year, suffering four first-round exits since May – three of them due to injury retirements.

The US Open will begin on August 28 in New York.

-AAP

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